david petraeus resigns at the cia after the fbi uncovers his extramarital affair. pierre thomas is here with the latest. first came upon this several months ago. >> yes, it came to light after a woman in tampa tied to military got a peculiar, harassing e-mail. the woman was so concerned, she contacted the fbi, who, then, according to our sources, traced it back to paula broadwell, who wrote a book about petraeus. as the fbi continued to investigate, they discovered e-mails pointing to a romantic, sexual relationship between the two. early concerns about the e-mails being hacked. but the investigation never turned up evidence of national security being compromised. but what did find was lots of human drama. >> what more do they have to investigate now and why wasn't the white house told until this week? >> the fbi investigation is largely done and the early evidence is that there will not be criminal charges. again, sources say that this deinvolved into a personal matter. petraeus had been confronted in the last couple of weeks, as for the timing of the disclosure,